Electron discharge device and method of making the same



T. E. FOULKE July 10, 1934.

ELECTRON DISCHARGE DEVICE AND METHOD OF MAKING THE SAME Filed Dc. 1?, 192a $65 trode 11.

able part in the interior of said envelope 1 is pro- Patented July 10, 1934 UNITED STATES ELECTRON DISCHARGE DEVICE AND METHOD OF MAKING THE SAME Ted E. Foulke, Nutlcy, N. J., assignor to General Electric Vapor Lamp Company, Hoboken, N. J., a corporation of New Jersey Application December 17, 1926, Serial No. 155,381

6 Claims.

The present invention relates to electron discharge devices and methods of preparing and making them. The invention more particularly relates to a method and means for producing a coating on an electron emitting electrode of a material which under operating conditions is a good or prolific source of electrons.

Various objects and advantages of the invention will be obvious from the following particuw lar description of one form of apparatus and of the method of producing it embodying the invention or from an inspection of the accompanying drawing; and the invention also consists in certain new and novel features of construction and combinations of parts hereinafter set forth and claimed.

The invention further consists in the new and novel features of operation and the new and original arrangements and combinations of steps in 2d the process hereinafter described and more particularly set forth in the claims.

In the accompanying drawing there is shown for purposes of illustration one form of electron discharge ,device embodying the invention, in

% which is shown in part in elevation and in part diagrammatically a three element electron dis-. charge device and means for producing a. sputtered coating of electron emission material on the filament thereof.

1n the drawing the closed envelope 1 connects through the tribulation 2 and the stop cock 4 to a source of gas or vapor not shown. Through the stem 6 of the envelope 1 are sealed the plate electrode 8, grid electrode 10 and thefilament elec- Over said stem 6 or at any other suitvided a deposit of material 12 which is under operating conditions a good or prolific source of electrons. Materials suitable for such use are oxides, (iii hydroxides or carbonates of strontium, barium, calcium, magnesium, lithium, potassium or the lih A source of current potential 14 is connected through the wires 15 and 16 respectively to' said plate 8 and one side of said filament 11. For the purposes of this invention connection from said source is made to any two of said electrodes, or two or more can be connected to one side of source and another to the other side.. In the use of the apparatus described for'producing a coating of electron emissive material on said filament 11, a filling of gas or vapor such as argon, neon or the like or mercury vapor is admitted'to envelope 1 through said tubulation 2 and the tubulation then preferably closed. A glow discharge is then produced in said gas by applying a space potential across any two of said electrodes 8, 10 or 11, as for example, by connecting a suitable source of current potential 14 through wires 15 and 16 tosaid electrodes 8 and 11 respectively. The discharge is continued for a predetermined time to bombard said material 12 and to sputter a coating thereof over said filament electrode 11.

When using the oxides, hydroxides, carbonates of any of the elements above cited, namely, calcium, magnesium, lithium, sodium and the like 65 the metal compound is first sputtered and deposited through the bombardment, and this deposit can be used on the filament 11 as a prolific source of electrons therefor. The sputtering, however, can be continued to such on extent that the deposited metal compound on the filament is reduced to the oxide and metal or until the material deposit 12 vhas been reduced to the pure metal and the pure metal sputtered over said filament 11. A pure metal deposit can also be used as the electron emission source.

In some cases it is desirable both, for the compound to serve as the electron emission material on the filament and also in order to secure a sufiiciently heavy deposit thereon to continue the 30 sputtering until a coating of the reduced metal is produced over the filament. In such cases to secure the desired results the sputtering is continued through the step of sputtering the metal compound on the filament and to and includin the step in which a coating of the pure metal is produced thereon. The glow discharge supporting gas is then evacuated from envelope 1 and a filling of oxygen is supplied in place thereof. 'Current is then passed through said fila- 9 ment 11 to heat it to a desired degree to cause the metal coating to react to the oxygen filling and produce the oxide thereof. An oxide coating having been formed on the filament the oxygen filling is removed from the envelopel and after suitable operations of pumping and cleaning well known in the art, the envelope is supplied with a filling of a gas suitable for supporting electron emission discharge and sealed off, or'the lamp is substantially completely evacuated and sealed off. 00 Gases suitable for supporting electron space discharge are those of the argon group, hydrogen and so on.

Although I have shown and described and have pointed out in the annexed claims certain novel features of the invention, it will be understood that various omissions, substitutions and changes in the several steps of the process and in its operation and in the form, details and operation of the apparatus illustrated may be made by those vice havingan electron emitting electrode or electrodes therein which consists in supplying the device with a material which is a source of electrons, evacuating said device, supplying said device with an inert gaseous atmosphere and sputtering a layer of said material on said electrode or electrodes by producing .a glow discharge in the gaseous atmosphere. v

2. The method of producing a coating of electron emissive material on an electrode of an electric space discharge device which consists in supplying said device with a quantity of said material in sputtering relation to said electrode, evacuating said device, supplying said device with an inert gaseous atmosphere and sputtering said material onto said electrode by producing an electric glow discharge in said device.

3. The method of producing a deposit of electron emitting material' on a discharge electrode which consists in sputtering the material thereonto from a source by ionic bombardment of the .source by a glow discharge in an inert gas havinga low ionizing potential.

4. The method of preparing an electron discharge device having a container'and electrodes therein one of which is an electron emitting electrode which consists in supplying the container with a source of electron emitting material evacuating said device, supplying said device with an :inert gaseous atmosphere and producing a glow discharge between electrodes of the device to cause ionic bombardent of the said source to sputter a coating of the material onto said electron 6: The method of producing a coating of electron emissive material on the cathode ofan elec tric discharge device which consists in-supplying said device with a quantity of electron emissive material in sputtering relation to said cathode, evacuating said device, supplying said device with an inert gaseous atmosphere and sputtering said material onto said cathode by producing an electric glow discharge in said device.

TED E. 'FOULKE. 

